Some mobile network operators are investigating the possibility of providing home and/or small area coverage for a limited number of users using a small base station, commonly called a “femto” base station (or femto NodeB for WCDMA or femto eNodeB (E-UTRAN NodeB) for long term evolution (LTE)). Other common names are Home NodeB (HNB) for WCDMA or Home eNodeB (HeNB) for LTE.
A femto base station may provide normal LTE/WCDMA coverage for end users in a so called femto cell, and may be connected to the mobile operator's network using some kind of IP based transmission. One alternative is to use fixed broadband access (e.g. xDSL or Cable) to connect the femto base station to the network.
In some systems (e.g., LTE systems) the coverage area (i.e., femto cell) of a femto base station may overlap with the cell of a large base station, commonly called a “macro” base station, and the femto base station may use the same frequency spectrum (or part of the same frequency spectrum) as the macro base station. Accordingly, at times, the users of the femto and/or macro base station may experience uplink and/or downlink interference. This interference is referred to as “macro-femto interference”. In this document, for purposes of brevity, the overlaying cellular network is always referred as “macro” layer, even though it may consist of both macro, micro and pico cells.
Thus, there exists a need to reduce this macro-femto interference.